Compound Particles and Product Manufactured Therefrom

ABSTRACT

A compound particle and a product manufactured from the compound particles are provided to solve a problem of a rough surface of a product made by additive manufacturing technology. The compound particle has a metal core and a ceramic shell wrapping the metal core. A melting point of the ceramic shell is higher than a melting point of the metal core.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure generally relates to a particle structure and, more particularly, to compound particles adapted for additive manufacturing technology and the product manufactured from the compound particles.

2. Description of the Related Art

Conventional objects are generally manufactured through molding, casting, grinding, etc. Take turbine rotor as an example, the surface roughness of conventional precision casting turbine rotor shall be larger than 1 μmRa and the yield rate is thus low. In addition, the exterior of the product is complicated for making a wax mold, the processing time is long, and the cost is also high. Particularly, it is commonly seen that the product has cavities and defects making subsequent processing, such as the polishing of the blades, difficult.

With the advance of science and technology, technologies such as sintering and additive manufacturing are further developed. For example, power bed fusion (PBF) technology adopts powders layer-by-layer to form the exterior of an object at different heights. Afterwards, it uses a heat source (such as an electron beam, a laser beam, etc.) to melt the powders in the same layer be melted and bound together. Thus, various objects such as precision components can be efficiently and effectively “manufactured”.

However, as shown in FIG. 1, common laser melting technology adopts heat source H1 (such as a laser beam) to melt conventional bulk material B1, then turn the bulk material B1 into liquid melt pool M1. The liquid flow in the melt pool M1 is mainly controlled by capillary oscillation and thermo-capillarity. The thermo-capillarity is the major cause of a rough product surface. When the bulk material B1 receives more energy than a threshold energy value T1, the thermo-capillarity and the surface roughness become higher following the increase of energy. Thus, it is needed that the thermo-capillarity be slowed down or delayed to reduce the surface roughness of the product.

Therefore, it is necessary to improve the disadvantages of the conventional bulk material to meet the actual need and to improve the applicability.

SUMMARY OF THE INVENTION

To solve the problem, the disclosure provides a compound particle which can increase the threshold energy value to delay the occurrence of thermo-capillarity and to enhance the capillary oscillation impedance.

The disclosure provides a product manufactured from compound particles with decreased surface roughness of the product.

The disclosure provides a compound particle which may have a metal core and a ceramic shell wrapping the metal core. A melting point of the ceramic shell may be higher than a melting point of the metal shell.

The disclosure also provides a product manufactured from the compound particles.

The metal core may have a material selected from titanium, stainless steel, aluminum alloy, titanium alloy, cobalt-chromium alloy, and nickel-based alloy. The metal core may have a diameter between 30 and 120 mm. The ceramic shell may have a material selected from tricalcium phosphate, hydroxyapatite, alumina, silicon carbide, silicon dioxide, titanium dioxide, and zirconia. The ceramic shell may have a thickness between 50 and 100 nm. Accordingly, the compound particle may be adapted for conventional powder bed fusion technology, such as being used for powder bed fusion of 3D printing, to reduce the surface roughness of the product.

The melting point of the metal core may be between 660 and 1700° C., where the melting point of the ceramic shell may be higher than 1700° C. but not higher than 2500° C. Alternatively, the melting point of the ceramic shell may be between 1000 and 2500° C., where the melting point of the metal core may not be lower than 660° C. but may be lower than 1000° C.

The compound particle and the product manufactured therefrom may have the ceramic shell wrapping the metal core with the melting point of the ceramic shell higher than the melting point of the metal core. Accordingly, when the compound particle is used in additive manufacturing (such as power bed fusion) technology, the threshold energy value and the viscosity may be increased to delay the occurrence of thermo-capillarity, to enhance the capillary oscillation impedance and to increase the efficiency of the capillary oscillation impedance. The surface roughness of the product manufactured by additive manufacturing technology may be effectively improved. The compound particle provides an effect of “reducing the surface roughness of the product” and is adapted for additive manufacturing product to increase the industrial value.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosure, and wherein:

FIG. 1 shows the liquid flow of conventional bulk material adopted in melting process.

FIG. 2 is a cross sectional view of a compound particle in the embodiment.

FIG. 3 shows the liquid flow of the compound particles in the embodiment adopted in additive manufacturing technology.

FIG. 4 is a comparison on surface roughness of additive manufacturing products adopting the compound particles in the embodiment and conventional metallic bulk material.

In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “inner”, “outer”, “side”, “top”, “bottom”, “front”, “rear”, “left”, “right” and similar terms are used hereinafter, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings, and are utilized only to facilitate describing the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 is a cross sectional view of a compound particle in the embodiment. The compound particle has a metal core 1 and a ceramic shell 2. The ceramic shell 2 may wrap the metal core 1 in whole or in part. A melting point of the ceramic shell 2 is higher than a melting point of the metallic shell 1. The illustration of the embodiment below is exemplary and not limitative.

Referring to FIG. 2, the metal core 1 may have a material selected from titanium, stainless steel, aluminum alloy, titanium alloy, cobalt-chromium alloy, and nickel-based alloy. The metal core 1 may have a diameter d between but not limited to 30 and 120 μm. The ceramic shell 2 may have a material selected from tricalcium phosphate, hydroxyapatite, alumina, silicon carbide, silicon dioxide, titanium dioxide, and zirconia. The ceramic shell 2 may have a thickness t between but not limited to 50 and 100 nm. Accordingly, it may be adapted for conventional powder bed fusion, such as being used for powder bed fusion of 3D printing, to reduce the surface roughness of the product.

In the present embodiment, the melting point of the metal core 1 may be between 660 and 1700° C., and the melting point of the ceramic shell 2 may be between 1000 and 2500° C. For example, when the melting point of the ceramic shell 2 being between 1000 and 2500° C., the melting point of the metal core 1 may not be lower than 660° C. but may be lower than 1000° C.; when the melting point of the metal core 1 being between 660 and 1700° C., the melting point of the ceramic shell 2 may be higher than 1700° C. but not higher than 2500° C., to maintain the melting point of the ceramic shell 2 higher than the melting point of the metal core 1.

Referring to FIG. 3, it shows the liquid flow of the compound particles in the embodiment adopted in additive manufacturing technology. Because the ceramic shell 2 of the compound particle B2 has the melting point higher than the melting point of the metal core 1, a threshold energy value T2 of the compound particle B2 may be raised. When the compound particle B2 is used in additive manufacturing technology (such as powder bed fusion), a heat source H2 (such as a laser beam) is used to melt the compound particle B2 to have the metal core 1 thereof turned into liquid and become melt pool M2. The ceramic shell 2, which remains unmelted, of the compound particle B2 may change a surface tension of the melt pool M2, and increase a viscosity of the melt pool M2. Thus, the occurrence of thermo-capillarity of the liquid flow of the melt pool M2 may be delayed to enhance capillary oscillation impedance. An amplitude A of the capillary oscillation impedance may decrease over time to increase an efficiency of the capillary oscillation impedance. Accordingly, when the applied energy increases, the surface roughness of the additive manufacturing product may be significantly reduced.

Referring to FIG. 4, it shows a comparison on surface roughness of laser melted compound particle in the embodiment and conventional metallic bulk material. A curve C1 shows the surface roughness of the conventional bulk metallic material consisting of nickel (Ni). The surface roughness of the compound particle of the present embodiment, which adopts nickel (Ni) for the metal core and nanosized aluminium oxide (Al₂O₃) for the ceramic shell, is shown as a curve C2. Regime transitions of curves C1 and C2 are marked with “*”. According to the drawing, the compound particle of the present embodiment having a structure of the ceramic shell wrapping the metal core may be used to make a product of compound particles, such as using additive manufacturing technology, to effectively improve the surface roughness.

Therefore, the above embodiment actually uses the ceramic shell to wrap the metal core due to the characteristic that the melting point of the ceramic shell 2 is higher than the melting point of the metal core 1. When being used in additive manufacturing (such as powder bed fusion) technology, the threshold energy value and the viscosity may be increased to delay the occurrence of thermo-capillarity. Accordingly, the capillary oscillation impedance may be enhanced and the efficiency of the capillary oscillation impedance may also be increased. Therefore, the surface roughness of the additive manufacturing products may be effectively improved. The present embodiment has an effect of “reducing the surface roughness of the product” and is adapted for additive manufacturing products to increase the industrial value.

Although the disclosure has been described in detail with reference to its presently preferable embodiments, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the disclosure, as set forth in the appended claims. 

What is claimed is:
 1. A compound particle, comprising: a metal core; and a ceramic shell wrapping the metal core, wherein a melting point of the ceramic shell is higher than a melting point of the metal core.
 2. The compound particle as claimed in claim 1, wherein the metal core comprises a material selected from titanium, stainless steel, aluminum alloy, titanium alloy, cobalt-chromium alloy, and nickel-based alloy.
 3. The compound particle as claimed in claim 1, wherein the metal core has a diameter between 30 and 120 μm.
 4. The compound particle as claimed in claim 1, wherein the ceramic shell comprises a material selected from tricalcium phosphate, hydroxyapatite, alumina, silicon carbide, silicon dioxide, titanium dioxide, and zirconia.
 5. The compound particle as claimed in claim 1, wherein the ceramic shell has a thickness between 50 and 100 nm.
 6. The compound particle as claimed in claim 1, wherein the melting point of the metal core is between 660 and 1700° C.
 7. The compound particle as claimed in claim 6, wherein the melting point of the ceramic shell is higher than 1700° C. but not higher than 2500° C.
 8. The compound particle as claimed in claim 1, wherein the melting point of the ceramic shell is between 1000 and 2500° C.
 9. The compound particle as claimed in claim 8, wherein the melting point of the metal core is not lower than 660° C. but lower than 1000° C.
 10. A product manufactured from compound particles, wherein the product is manufactured from the compound particles as claimed in claim 